Are MFA sites illegal?

MFA is an inventory-quality label, not a legal category, so the label alone does not tell you whether a site is lawful. Whether particular practices break the law depends on the jurisdiction and the facts, for example if a site copies other publishers' content or generates invalid traffic, and a qualified lawyer should review a specific site or campaign. DoubleVerify notes that, unlike ad fraud, MFA inventory is not inherently invalid and that some advertisers choose to run on it; others exclude or limit it under their own brand-suitability policies, and the ANA's June 2023 release recommended excluding MFA sites from a media buy unless they are specifically wanted or needed.

How can I tell if a site is MFA?

No single signal is proof: DoubleVerify, for example, says a site with many ads but high direct and search traffic would not meet its definition. Signals that the ANA and verification vendors cite include a high ratio of ads to content, frequent ad refresh, pop-ups or autoplay video, low-quality or duplicated content, and traffic that comes mostly from paid sources rather than organic or direct visits. Treat them as reasons to review a site by hand against criteria you have documented.

Do MFA sites appear in native ad networks?

They can. Native units and widgets run on the publisher sites that a network, exchange or buyer can reach, so check where your ads actually ran in your own placement reports. OpenAdLibrary records the publisher domain where it observed a native placement, but that record does not by itself show whether a domain is MFA.

Definition

What Are Made-for-Advertising (MFA) Sites?

Q: Who publishes MFA exclusion lists?

MFA classifications come from several sources rather than one authority. Verification vendors such as DoubleVerify and Integral Ad Science classify MFA sites in their own products, IAS says it trained its model against Jounce Media's widely adopted list of MFA domains and the ANA's definition, and the ANA's June 2023 study release recommended that advertisers demand MFA sites be excluded from a media buy unless they are specifically wanted or needed. Definitions, criteria and coverage differ, so check what a list contains and how it was built before relying on it.

MFA sites are built to generate ad revenue rather than serve readers, typically thin on content and heavy on ad units and cheap paid traffic.

The OpenAdLibrary TeamAd intelligence & native advertising research

September 5, 2026 · Updated October 25, 2026 · 2 min read

Editorial illustration: What Are Made-for-Advertising (MFA) Sites?

Made-for-advertising (MFA) sites are websites built primarily to generate ad revenue rather than to serve readers. Definitions vary by source. The ANA's June 2023 study release says MFA sites usually feature low-quality content and may use tactics such as pop-up ads, auto-play videos or intrusive ads to maximize ad revenue, and verification vendors add signals such as a high ratio of ads to content, frequent ad refresh and traffic that comes mostly from paid traffic sources, such as social platforms and content discovery networks, rather than from organic search or direct visits. DoubleVerify, for example, says a site with many ads but high direct and search traffic would not meet its definition, so one trait is not proof.

Why MFA sites exist#

Programmatic advertising pays publishers for ad impressions and clicks, not for reader value, and MFA operators build sites to capture that revenue; IAS describes MFA sites as built to conduct ad arbitrage, paying for traffic and earning more from the ads shown to it. As a hypothetical example, a site of scraped or lightly rewritten articles with several ad units per page, fed by purchased traffic, is profitable if the ad revenue it earns per visit (see RPM) exceeds what each visit cost to buy, even with almost no audience loyalty. Standards for the ad supply chain answer a different question: ads.txt and sellers.json show who is authorized to sell a domain's inventory, not whether the content is worth advertising against, so an authorization entry is not evidence of editorial quality.

How they get flagged#

Verification vendors classify sites using signals such as the ratio of ads to content, ad refresh rate, traffic source and content originality. Integral Ad Science lists ad-to-content ratio, number of ads, auto-refresh, refresh rate, traffic source and autoplay video among its signals, and DoubleVerify sorts sites into High, Medium and Low MFA tiers using monetization, traffic-source and content-creation factors. ads.txt and sellers.json help buyers check which sellers a domain has authorized and who those sellers are; IAB Tech Lab describes them as transparency tools for seller authorization and the supply chain, and neither assesses content quality. MFA classifications differ by source: IAS says it trained its model against Jounce Media's widely adopted list of MFA domains and the ANA's definition, and the ANA's June 2023 study release recommended that advertisers demand MFA sites be excluded from a media buy unless they are specifically wanted or needed. Check what any list contains and how it was built before applying it.

Why it matters for advertisers#

Many advertisers avoid MFA inventory for media-quality and brand-suitability reasons, and how much of a campaign lands on it varies. In the ANA's 2023 study, MFA sites accounted for 21% of study impressions and 15% of ad spend (September 2022 to January 2023, covering $123 million of spend and 35.5 billion impressions from 21 ANA member companies). The ANA's later Programmatic Transparency Benchmark reported MFA domains at 0.39% of spend in Q3 2025 and an MFA exposure of 1.1% in Q1 2026 among participating advertisers. The samples and methods differ, so the figures show how widely exposure can vary, not a market share.

Outcomes on MFA inventory also vary by campaign. IAS reported in March 2024, across analyses for more than 40 agencies and brands, weaker conversion results on sites it classifies as MFA, but its release gives no method, and DoubleVerify notes that MFA inventory is not inherently invalid and that some advertisers choose to run on it, so your own placement reports and results are the evidence that matters. This overlaps with concerns about content farms and low-quality publisher networks more broadly. Media buyers running native campaigns can compare a network's placement reporting with the publisher domains that OpenAdLibrary's ad intelligence pages record for the placements it captured; those records are a sample, not every placement of a campaign, and a domain's presence in them does not show whether it is MFA.

A practical checklist#

Before treating a new publisher domain as acceptable inventory, review it against criteria you have written down. Look at real pages: how much original content the site publishes, how many ads load on a typical page and how they behave (refresh, pop-ups, autoplay). Check any vendor classification you use and what it is based on. Where a verification or traffic-estimation source is available, check whether the site's traffic comes mostly from paid sources. Check the site's ads.txt and sellers.json declarations. Each signal is a reason to look closer, not proof: a high ad load alone does not make a site MFA, and an authorized-seller entry does not make it good. Make the decision on documented criteria with a human review, record it, and re-review on a schedule that fits your spend.

Related terms: Publisher, ads.txt, and Ad Supply Chain.